The present invention relates generally to a fluid pressure cylinder, and more particularly, to an improved fluid pressure, rodless cylinder of the type having a cylinder with an enlongated, longitudinally extending slot, a piston reciprocally movable within the cylinder and an improved sealing means for successively sealing the slot during reciprocal movement of the piston.
Pressure cylinders, and in particular rodless, pressure cylinders, have existed in the art for many years. In general, a rodless fluid pressure cylinder includes an enlongated cylinder with a slot extending along the wall of the cylinder in an axial direction. A piston member is disposed within the cylinder for reciprocal back and forth movement along the length of the cylinder. Such movement is controlled by the introduction of hydraulic or pneumatic fluid pressure into chambers at the ends of the cylinder on each side of the piston. Such cylinders also include means for transferring the reciprocal movement of the piston to an external workpiece. In a rodless cylinder this means normally includes a bracket connected directly with the piston and having a portion extending outwardly through the elongated slot for connection with the work piece. Because of this elongated slot in the cylinder element, a seal member is needed to seal the pressure chambers in the opposite ends of the cylinder to prevent the fluid pressure from escaping through the slot.
One prior art structure is shown in U.S. Pat. No. 3,820,446. The device of this patent contemplates the use of a flat sealing member having magnetic properties which is adapted for engagement with the inside surface of the cylinder on opposite sides of the slot. The sealing member in this patent is retained in this sealing position by a plurality of magnet elements embedded within the cylinder wall. A second prior art structure is shown in U.S. Pat. No. 4,373,427. This patent contemplates that the cylinder wall will be made of steel or other material having magnetic properties and that the elongated sealing member would be a relatively flat member having a portion constructed of a rubberized magnet for attraction to the steel wall.
While both of these prior art structures as well as others have performed satisfactor:ly in certain applications, there continue to be ways in which fluid pressure cylinders of this type can be improved. For example, efforts are continually being made to improve the sealing relationship between the elongated sealing member and the portions of the cylinder wall dividing the elongated slot. Further, efforts are also continually being made to increase the life and wearability of the seal member since such seal must be able to withstand millions of cycles without failing. Finally, efforts are always being made to construct an improved fluid pressure cylinder at a reduced cost. Thus, a need continues to exist in the art for a power cylinder having the above-mentioned improvements and features.